While looking up something in Andrew Roberts's outstanding biography of the 3rd Marquess of Salisbury, Tory Historian came across the following paragraph, which raises a number of interesting points about the role and duty of MPs:

When Lord Randolph Churchill emerged as the leader of the movement for Party democracy in 1883 and 1884, Salisbury set his face against anything that he considered liable to fetter the complete independence of parliamentarians, as famously enunciated in Edmund Burke's 1774 address to the electors of Bristol. He was not about to allow parliamentary sovereignty to be circumscribed by caucuses of Party bureaucrats, let alone rank-and-file Party members.

Control of Parties from outside Parliament both seemed to Salisbury impractical as it could not take into account the fast-moving mood swings of the Commons chamber, and repugnant in a Constitution in which an MP was expected to represent his whole constitutency, not just that part of it which voted for him.

There were, therefore, philosophical as well as practical considerations why Salisbury and Churchill were set upon a collision course.

It is an interesting and unexpected use of the term parliamentary sovereignty, which is not usually applied to the relationship between MPs and other party members.

There are also other issues. Edmund Burke was talking about whether MPs should represent their constituents' wishes or vote according to their conscience and view of what was best for the country. But, undoubtedly, it is important to recall that an MP must, if he or, these days, she is to represent directly the constituents, it must be all of them. Then again, should the said MP remain in thrall to those constituents, anyway? Probably, if a re-election is sought, but that is a somewhat cynical point of view.

Of greater interest is the role of the leaders of the party in parliament, who, also want to control MPs. What should their role be? Tory Historian can probably guess what the great marquess would have said but the whole issue remains unresolved with different groups emerging victorious at different times.